This invention relates to telephony systems which process incoming calls, and, more particularly, to fault tolerant arrangements to maintain uninterrupted call processing.
Telephony systems of different types are available for a variety of applications. A typical application involves processing of informational inquiries by callers using an xe2x80x9c800xe2x80x9d type telephone service. An incoming call is routed to one of a number of application processor stations (or nodes) which may be a computer workstation enabling access to an individual prepared to provide personal service, to a voice operating system and to other capabilities suitable for providing a response to caller inquiries.
Upon occurrence of a short or longer term equipment or other failure affecting a call while it is being responded to via an application processor, an incoming call may be interrupted or lost. Such call interruption or loss can result in user-call back, user irritation and dissatisfaction, operating inefficiency, etc.
Approaches to alleviating this type of problem have typically relied upon standby-redundancy or hardware-redundancy with synchronization aspects. In the former, a standby processor may be provided, with provision to assume the role of a disabled processor node and restart application capabilities. Nevertheless, calls in progress may typically be lost or interrupted. In the latter, more complex computers arranged with hardware running in parallel for fault tolerant operation may be configured to include synchronization capabilities intended to enable call handoff. Such prior configurations, which as a practical matter may not be able to maintain call processing when a failure occurs, are generally subject to one or more disadvantages such as excessive cost, excessive complexity, inability to avoid call interruption or loss, and low reliability under actual operating conditions.
Accordingly, provided is a call-protect handoff system, fault responsive to maintain processing of a user-call, including a user-call controller to route a user-call and an application processor (AP) node. The user-call controller includes memory having call context information storage to store context information regarding user-calls while such calls are in progress. The AP node includes two call processing (CP) facilities. An active CP facility is communicatively-coupled to the user-call controller such that the active CP facility can process user calls routed by the user-call controller. A standby CP facility is coupled to the same or another user-call controller such that upon a failure event affecting the active CP facility processing a user-call, the user-call controller communicatively-couples the standby CP facility to maintain processing of that user-call for continued processing supported by use of call context information stored for that user-call in the call context information storage.
In a further aspect, a network call-protect handoff system is provided. The system includes a call processing subsystem to receive user-calls, with a plurality of user-call controllers. Each user-call controller is arranged to control at least one specific user-call and the subsystem includes memory to store call context information regarding that call. The system includes a coupling arrangement, such as a local area network. A plurality of application processor (AP) nodes are coupled via the coupling arrangement to the call processing subsystem to process user-calls. Each AP node includes at least two call processing (CP) facilities (i) an active CP facility coupled to one user-call controller and (ii) a standby CP facility. The system is configured with each user-call controller actively coupled to the active CP facility of a selected AP node for processing of the specific user-call. Each user-call controller is arranged, upon a failure event affecting the selected AP node, to cause handoff of the specific user-call to an available standby CP facility of a different AP node to maintain processing of that call by use of call context information retrieved from memory. The AP node processing a user-call is arranged, in cooperation with an associated network interface card in the user-call controller, to store such call context information in the memory (e.g., in a call context information storage) while the call is being processed. Upon occurrence of a failure event, the AP node receiving handoff of the call is arranged to access stored call context information from the memory, to maintain processing of the call. To facilitate uninterrupted handoff, standby CP facilities are typically arranged to run in a standby mode when no user-call controller is actively coupled thereto.
For a better understanding of the invention, together with other and further objects, reference is made to the accompanying drawings and the scope of the invention will be pointed out in the accompanying claims.